Rigid paper containers for product packaging are frequently constructed from boxes or containers folded from corrugated paper. The fabrication of corrugated boxes, folding carton containers, and other packaging materials involves a series of forming operations all of which are subject to errors that can result in the end container being unacceptable for its intended purpose.
With the drive towards greater economic efficiency the manufacture of cardboard boxes has been vertically integrated such that the producer of the original cardboard stock will often perform the box fabrication. In this manner transportation and handling of the packaging is reduced as is the profit lost to third parties. Increases in the automation of box assembly, for example utilizing case erecting equipment, offer the opportunity to reduce cost, however for this automation to be cost effective high quality box blanks must be provided. Poor quality blanks exhibiting inadequate or inappropriate gluing, scoring, incomplete or incorrect die cutting, or poor substrate quality, may cause the case erection equipment to jam or otherwise malfunction resulting in very expensive down time.
A further driver of improvement in box manufacture is the out-sourcing of production and even end product inventories with the goods manufacturer relying on respectively just-in-time delivery of packing materials or indirect shipments of the final packed goods directly to end customers and distribution channels. This increases pressure to assure the quality of the packaging which will enclose the goods as the cost of errors caught late in the supply chain increases with vertical integration and just in time inventory techniques.
A yet further trend is the differentiation of the end goods through its packaging. Increasingly the containers are being relied upon to differentiate the end product through advanced printing, embossing, die-cutting, folding and scoring techniques. As the operations performed on the box both increase in number and complexity, the opportunity for unacceptable errors to be introduced also increases as does the cost of these errors resulting from scrapping the increasingly valuable box.
A further trend is the increased regulation of the packaging industry as the manufacturers who produce regulated product, such as pharmaceuticals, food stuffs and medical equipment companies, themselves face increasing governmental regulation. As regulation of the end product increases, pressure increases on suppliers of packaging to the regulated industry to adopt repeatable and transparent processes and to assure to their customers and their regulators that the goods they ship have followed these processes and have been produced within acceptable tolerances.
As can be seen from the combination of these market pressures, the value of delivering a “perfect box” to an end customer has increased, yet the innovation to assure the delivery of “perfect boxes” has not increased commensurate with the need.
Rigid paper containers, can be made on a variety of equipment. Common fabrication machines include integrated flexo/folder/gluers which receive blanks of cardboard from corrugation machines, print the walls of the blank with decorative patterns, labels and tracking symbols, die cut holes and shapes into the blank, score fold lines, apply glue and then perform initial folding of the blank. Other equipment, such as specialty gluers, may perform folding and gluing, while die-cutters typically perform printing, scoring, and die-cutting. Still others may perform any single or combination of these operations. A characteristic of this equipment is that its design life may be decades in length, and capital may not be available to replace it, thus requiring field upgrade of the equipment if technical innovations are to be applied to improve the equipment's capabilities. As the new capability being upgraded into the machine was frequently not envisioned (nor even feasible) at the time the equipment was originally designed and built, the space available to retrofit functions is by necessity constrained if available at all.
It is in the nature of box blank finishing and box production equipment that it is versatile, being able to produce a variety of boxes or cartons on various substrate stock, of various sizes, base colors and shapes, in varying quantities and employing a range of adhesives the color and properties of which may also vary. Also, the throughput of the production equipment may be changed between runs or within runs as the quality of the substrate and finishing operations varies. Further, judging the quality of the box following the production operations must be done without interrupting or delaying the throughput of the production equipment, permitting rejected boxes to be identified, flagged for rejection, or mechanically sorted from acceptable product into a reject stream.
As should be clear from the afore-described situation, providing assurance against errors in box blank finishing in a transparent, auditable, robust, and easily-used manner has become increasingly important. To address this need a variety of technologies are known for assessing box fabrication operations, however none of these technologies, or methods employing such technologies, adequately addresses the need as has been outlined.
Conventional box blank finishing systems commonly include a sensor for detecting as a single parameter the presence of glues within a specified area along the direction of travel of the box blank, such as that described in U.S. Pat. No. 4,389,969. Such single-degree-of-freedom systems may monitor the level of a single measured parameter along the axis of blank travel such as humidity, capacitance, UV light absorption, light scatter, etc. and check for a strong sensor signal when glue is adjacent to the sensor relative to a weaker sensor signal when an unglued substrate is adjacent to the sensor. While such sensors may be satisfactory for gross verification of the amount of glue present on a blank in a well controlled environment, they are inadequate to check as to whether the pattern of glue laid down is correct. Additionally such single degree of freedom sensing systems are inadequate to capture or display a complete image of the box or for checking other parameters of the box such as print or fold quality. Further and in the case of moisture sensors they may give false positive readings of glue presence if the substrate contains a high level of moisture while being otherwise within specification.
Numerous systems are available which check for registration of printing. While most employ high resolution printer targets intended to be reviewed by a skilled printing machine operator from samples pulled from a print run, some automated print register control systems are available from companies such as Quadtech Inc for use on high speed sheet and web presses. While these systems operate at very high speeds and are capable of controlling printing register to a degree adequate for box manufacture, their capabilities rely on the use of area-scan cameras with unrestricted access to a specific and small field of the substrate. This is not desirable in box manufacturing where the entire box is to be checked for print and die cutting errors ideally by way of a narrow window across the substrate as it passes the camera and illumination source. In addition, automated print register control systems are specific-purposed systems not suitable for print as well as glue or die cut verification.
The present disclosure provides a method and apparatus for improving the delivery of the “perfect box” from the equipment currently used to produce paper-based packaging containers and to perform box blank finishing, in an inexpensive and robust manner in a physically form factor convenient for retrofit to installed equipment.